ConsoleCalculator

#include <iostream>
#include <string>
#include <stdlib.h>
#include <cctype>

using namespace std;

void MENU(); // Function prototype for MENU function
void Addition(); // Function prototype for Addition function
void Subtraction(); // Function prototype for Addition function
void RESTART(); // Function prototype for RESTART function

//Function prototypes used to keep the code clean and readable.

int main() //Main function
{

MENU(); // MENU first to run in the main

    return 0;
}

void MENU() //When called upon the basic main menu should show up.
{
    int answer; //answer variable used to navigate the menu
    int Addition(); //Function variable (i think) for Addition
    int Subtraction(); //Function variable possible for Subtraction

    cout << "     MENU\n"; //Text for the menu reading off the options the user has from 1 to 3
    cout << " 1.ADDITION\n";
    cout << "2.SUBTRACTION\n";
    cout << "   3.EXIT\n";
    cin >> answer; //User enters his answer

    switch(answer){ //Switch runs through its options based on that answer variable
case 1:// if case 1 is picked then it goes to the addition function
  Addition();
break;

case 2:// if 2 is picked then it goes to the subtraction function
    Subtraction();
    break;
case 3: // If the user enters 3 then it clears screen and ends the program.
    system("cls"); // a poor insecure way to clear the screen before exiting the program,
                  //but currently the only way i know how to get it to work the way i desire it to.
    exit(0);
    break;

default :
    cout << "PLEASE INSIERT 1, 2 OR 3\n";//Prompting user to pick a valid answer
    MENU();//Redirecting user back the MENU function
  }
}

void Addition() //When called upon the program should do a basic 2 number addition.
{
    int fn;
    int sn;
    int sum;

    cout << "       ADDITON\n"; //Very simplistic almost DOS like menu for the Addition user interface
    cout << "ENTER YOUR FIRST NUMBER:\n"; //Prompting user for first number
    cin >> fn; // User enters first number
    cout << "\nENTER YOUR SECOND NUMBER:\n"; //Prompting user for first number
    cin >> sn; // User enters second
    sum = fn + sn; //Program adds the two together
    cout << "\nYOUR TOTAL IS: " << sum << endl; //Program prints out sum
    cout << endl;
    RESTART(); // Supposed to ask if the user wants to restart, instead goes straight to menu
}

void Subtraction() //Everything here is supposed to act the same as addition
//except its main purpose is to subtract the second number from the first number
//but it fails the same way as the Addition function
{
    int fn;
    int sn;
    int sum;

    cout << "       SUBTRACTION\n";
    cout << "ENTER YOUR FIRST NUMBER:\n";
    cin >> fn; //All functions here are the same as addition with the exception it subtracts values rather than adds them
    cout << "\nENTER YOUR SECOND NUMBER:\n";
    cin >> sn;
    sum = fn - sn;
    cout << "\nYOUR TOTAL IS: " << sum << endl;
    cout << endl;
    RESTART(); // same issue happens as soon as it's supposed to hit this bit of code
}

void RESTART() //When called upon the program will restart or end the program, or so it should.
{
    string input;

    cout << "DO YOU WISH TO START OVER? Y/N"; //None of this makes an appearance in the code
    cin >> input;
if (input == 'y')
{
    MENU();
}else if(input == 'n')
{
    system("cls");// a poor insecure way to clear the screen before exiting the program
    //but currently the only way i know how to get it to work the way i desire it to.
    exit(0);
}


}